1. Field of the Invention
This invention relates generally to the generation of symmetrical analog waveforms and specifically to the generation of symmetrical analog waveforms by digital circuitry to which has been applied a digital pulse train.
2. Description of the Prior Art
It has been found that in some instances data transmission by and/or between digital computers or digital signal generating equipment can be better effected when the information is encoded for transmission in analog (multi-valued) form. Further, analog waveform generating circuits can provide a computer with the possibility of generating speech or music.
While conventional analog circuitry, utilizing inductive and capacitive elements, can be activated by digital computers to produce practically any type of analog waveforms desired, such methods are not without problems. For example, the equipment may be required to operate over a relatively wide temperature range. In order to operate satisfactorily over wide temperature ranges, the inductive and capacitive elements must have a low temperature sensitivity. Fabrication of such low temperature sensitivity elements can give rise to higher manufacturing costs. Another drawback lies in the bulky size of the inductors and capacitors required when low frequencies are desired.
Digital circuits, for the most part, do not require elements having strict electrical values or low temperature sensitivities, can usually operate on low power requirements, and are capable of miniaturization.